1. Field of the Invention
The present invention generally relates to a wrench assembly, and more specifically to a box wrench assembly that fits various kinds of screw pieces and provides a more convenient and faster way for the operation of the box wrench.
2. Description of the Related Art
Referring to FIG. 18, a box wrench assembly of a prior art has a polygonal groove 91 either in a dodecagonal shape or a hexagonal shape for engaging a screw piece, but such assembly has the following shortcoming:
Since screw pieces come with various different shapes including the gear, star, hexagonal and dodecagonal shapes, therefore a single polygonal groove 91 can only fit a single compatible screw piece, but not the screw pieces of various different shapes. Thus, the box wrench of this sort has poor expandability.